1. Field of the Invention
This invention relates to hot water heater circuitry, and particularly relates to a novel combination of a hot water heater with external heating means and to novel means for operatively connecting the two for efficient cooperation. In a more specific aspect, this invention also relates to specially configured conduits for carrying fluids into and out of tanks utilizing a single tank opening. More specifically, the novel features of the present invention are used in conjunction with a residential or other hot water tank and a supplementary water heating means, such as a solar water heating apparatus, a low compression heat pump and heat exchanger, or a hydronic boiler and heat exchanger, for example.
2. Description of the Prior Art
It is generally known to provide inflow and outflow means for handling fluids through a single tank opening. The patent to Hesse et al U.S. Pat. No. 4,124,137 discloses a vessel with several conduits passing through a single opening such that one conduit extends nearly to the bottom of the tank and the other conduit extends close to the top of the tank. This tank opening arrangement is at the top of the tank where no fluid would naturally flow out of the opening. Hesse et al disclose several tubes passing through a single tank opening.
The patent to Wittersheim et al U.S. Pat. No. 3,559,701 discloses a single opening combination fluid inlet and gas outlet valve for refilling aerosol spray containers. The problem of handling hot water in a heater, partially produced by an outside source, is not discussed.
An important application of the novel circuitry of the present invention is in the addition of supplemental heating means, such as a low compression heat pump, to existing residential or other water heating systems.
Existing heat pumps designed to supplement residential or other water heating systems require two openings in the hot water tank; one for cool water flowing out of the tank and into the heat pump and one for warm water flowing out of the heat pump and into the hot water tank. Generally, existing heat pumps have a cool water outflow line connected to the tank's drain opening. Since many of these heat pumps are sold as retrofit packages for existing hot water tanks, the requirement of two tank openings presents several problems. The first problem is the cost and bother of making an opening in the hot water tank.
In addition to the cost of cutting one additional opening in an existing hot water tank, many retrofitters attempt to cut costs and installation aggravation by making no additional openings in the hot water tank, using instead the tank's pressure-temperature relief valve opening as the second conduit opening for depositing water from the supplemental heat source. This creates an extremely dangerous situation. Explosive conditions in the hot water tank can be caused by tampering with the pressure-temperature relief valve when installing a sealed heat pump system line, thereby seriously endangering human life.
The novel circuitry of the present invention allows the addition of a supplemental heat pump for heating water without making an additional opening in the hot water tank and without disturbing the important safety function of the pressure-temperature relief valve.
An important characteristic of most hot water heaters is that a temperature gradient naturally exists vertically with the height of water in the tank. Thus, in the usual hot water heater tank there are water strata having different temperatures, with the warmest stratum being at an upper portion of the tank and the coolest stratum being at a lower portion of the tank. One of the major problems with the heat pumps of the prior art concerns their failure to take best advantage, or even to acknowledge the existence, of this temperature gradient. Specifically, prior art heat pump retrofits fail to deposit the warmed (e.g. 120.degree. F.) incoming water from the heat pump to the optimum usable position in the hot water tank without "temperature-dilution" of the even hotter water at the top of the tank. This is especially so when the pressure-temperature relief valve opening, required in many states to be placed within six inches of the top of the hot water tank, is used to convey the warm incoming water.
The novel circuitry of the present invention is able to deposit the warmed incoming water from the heat pump directly to that water stratum having a temperature substantially equal to the temperature of the incoming water. Thus, the novel circuitry of the present invention does not disturb the temperature stratification existing in the hot water tank and more importantly does not mix the warm incoming water with the even hotter water already existing at the top of the tank.